From mboxrd@z Thu Jan 1 00:00:00 1970 From: Greg KH Subject: [patch 05/37] bridge-netfilter: dont overwrite memory outside of skb Date: Wed, 6 Sep 2006 15:55:16 -0700 Message-ID: <20060906225516.GF15922@kroah.com> References: <20060906224631.999046890@quad.kroah.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Justin Forbes , Zwane Mwaikambo , "Theodore Ts'o" , Randy Dunlap , Dave Jones , Chuck Wolber , Chris Wedgwood , torvalds@osdl.org, akpm@osdl.org, alan@lxorguk.ukuu.org.uk, netdev@vger.kernel.org, Stephen Hemminger , Greg Kroah-Hartman Return-path: To: linux-kernel@vger.kernel.org, stable@kernel.org, David Miller Content-Disposition: inline; filename="bridge-netfilter-don-t-overwrite-memory-outside-of-skb.patch" In-Reply-To: <20060906225444.GA15922@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org -stable review patch. If anyone has any objections, please let us know. ------------------ From: Stephen Hemminger The bridge netfilter code needs to check for space at the front of the skb before overwriting; otherwise if skb from device doesn't have headroom, then it will cause random memory corruption. Signed-off-by: Stephen Hemminger Signed-off-by: Greg Kroah-Hartman --- include/linux/netfilter_bridge.h | 16 ++++++++++++---- net/bridge/br_forward.c | 10 +++++++--- 2 files changed, 19 insertions(+), 7 deletions(-) --- linux-2.6.17.11.orig/include/linux/netfilter_bridge.h +++ linux-2.6.17.11/include/linux/netfilter_bridge.h @@ -47,18 +47,26 @@ enum nf_br_hook_priorities { #define BRNF_BRIDGED 0x08 #define BRNF_NF_BRIDGE_PREROUTING 0x10 - /* Only used in br_forward.c */ -static inline -void nf_bridge_maybe_copy_header(struct sk_buff *skb) +static inline int nf_bridge_maybe_copy_header(struct sk_buff *skb) { + int err; + if (skb->nf_bridge) { if (skb->protocol == __constant_htons(ETH_P_8021Q)) { + err = skb_cow(skb, 18); + if (err) + return err; memcpy(skb->data - 18, skb->nf_bridge->data, 18); skb_push(skb, 4); - } else + } else { + err = skb_cow(skb, 16); + if (err) + return err; memcpy(skb->data - 16, skb->nf_bridge->data, 16); + } } + return 0; } /* This is called by the IP fragmenting code and it ensures there is --- linux-2.6.17.11.orig/net/bridge/br_forward.c +++ linux-2.6.17.11/net/bridge/br_forward.c @@ -43,11 +43,15 @@ int br_dev_queue_push_xmit(struct sk_buf else { #ifdef CONFIG_BRIDGE_NETFILTER /* ip_refrag calls ip_fragment, doesn't copy the MAC header. */ - nf_bridge_maybe_copy_header(skb); + if (nf_bridge_maybe_copy_header(skb)) + kfree_skb(skb); + else #endif - skb_push(skb, ETH_HLEN); + { + skb_push(skb, ETH_HLEN); - dev_queue_xmit(skb); + dev_queue_xmit(skb); + } } return 0; --